CVE-2020-8929

Name: CVE-2020-8929
Creator: NVD / NIST
Published: 2020-10-19T13:15:13.437+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.47%

Last modified Jun 17, 2026

CVE-2020-8929 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. A mis-handling of invalid unicode characters in the Java implementation of Tink versions prior to 1.5 allows an attacker to change the ID part of a ciphertext, which result in the creation of a second ciphertext that can decrypt to the same plaintext. This can be a problem with encrypting deterministic AEAD with a single key, and rely on a unique ciphertext-per-plaintext.. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

Description

A mis-handling of invalid unicode characters in the Java implementation of Tink versions prior to 1.5 allows an attacker to change the ID part of a ciphertext, which result in the creation of a second ciphertext that can decrypt to the same plaintext. This can be a problem with encrypting deterministic AEAD with a single key, and rely on a unique ciphertext-per-plaintext.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

0.47%

37.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-176

Affected Software

Vendor	Product	Versions
Google	Tink Java	< 1.5.0

References

https://github.com/google/tink/commit/93d839a5865b9d950dffdc9d0bc99b71280a8899Patch, Third Party Advisory
https://github.com/google/tink/security/advisories/GHSA-g5vf-v6wf-7w2rPatch, Third Party Advisory
https://github.com/google/tink/commit/93d839a5865b9d950dffdc9d0bc99b71280a8899Patch, Third Party Advisory
https://github.com/google/tink/security/advisories/GHSA-g5vf-v6wf-7w2rPatch, Third Party Advisory

Timeline

Published: Oct 19, 2020
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2020-8929?

How severe is CVE-2020-8929?

CVE-2020-8929 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2020-8929?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-8929?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST